1. Field of the Invention
The present invention relates to a lamp unit for a vehicle, and more particularly, to a projector-type lamp unit configured to form a light distribution pattern having a cutoff line.
2. Background Art
A projector-type lamp unit is one type of lamp unit for a vehicle. Related art projector-type lamp units include a projection lens disposed on an optical axis extending in a front-and-rear direction of the vehicle, a light source disposed on a rear side of a rear focal point of the projection lens, and a reflector which forwardly reflects a light emitted from the light source toward the optical axis.
In order to form a light distribution pattern having a cutoff line, e.g., a lower-beam light distribution pattern, which is also called as a passing-beam light distribution pattern, with a light irradiating from the projector-type lamp unit, a shade is provided near the rear focal point of the projection lens to shield a part of the light reflected by the reflector so that the cutoff line is formed as an inverted projection image of an upper edge of the shade (see, e.g., JP 2004-95481 A).
However, in the related art projector-type lamp units, the cutoff line formed as the inverted projection image of the upper edge of the shade is very clear, and the light is rarely irradiated toward an upper side of the cutoff line. Therefore, there has been a disadvantage in that visibility in a distant region of a road surface in front of the vehicle tends to be insufficient.